(1) Field of the Invention
The present invention relates to a structure in which the upper part of a front pillar of a truck, passenger car, bus, and the like vehicles is joined to a roof header member and a roof side member, and a structure in which the lower part of a pillar inner panel of a front pillar is joined to a cowl inner panel.
(2) Description of Related Art Including Information Disclosed Under 37 C.F.R. 1.97 and 1.98
The present applicant applied for patents for a vehicular front structure in which a front pillar of a front corner member is provided between the side edge of a windshield glass and the front edge of a side glass, and the front pillar is formed into a tubular shape by joining a pillar inner panel and a pillar outer panel to each other (for example, refer to Patent Document 1). In this vehicular front structure, as shown in FIG. 20, a roof panel 145 is integrally formed at the upper end of a pillar outer panel 132, and a cowl outer panel 163 is integrally formed at the lower end of the pillar outer panel 132. Also, a side inner panel 146 is joined to the upper end of a pillar inner panel 131, and a cowl inner panel 161 is joined to the lower end of the pillar inner panel 131. On the other hand, an outer front-side flange 132b provided at the front edge of the pillar outer panel 132 is joined to an inner front-side flange 131b provided at the front edge of the pillar inner panel 131, and a roof front-side flange 145c provided at the front edge of the roof panel 145 is joined to a header front-side flange 144b provided at the front edge of a header inner panel 144. Also, a cowl outside flange 163a provided at the upper edge of the cowl outer panel 163 is joined to a cowl inside flange 161a provided at the upper edge of the cowl inner panel 161.
On the other hand, an upper joint structure of a front pillar 217 has been known in which, as shown in FIGS. 21 and 22, the upper part of a pillar inner panel 231 of the front pillar 217, the side end part of a header inner panel 244 of a roof header member 241, and the front end part of a side inner panel 246 of a roof side member 242 are joined to each other by an upper joint panel 243. In this upper joint structure, the upper part of the pillar inner panel 231 is joined to the front end of the side inner panel 246 of the roof side member 242. Also, by the upper joint panel 243, the upper part of the pillar inner panel 231, the front end part of the side inner panel 246, and the side end part of the header inner panel 244 of the roof header member 241 are joined to each other. At this time, the upper joint panel 243 is provided on the outside of a cab from the pillar inner panel 231.
Also, a lower joint structure of the front pillar 217 has been known in which, as shown in FIGS. 23 and 24, the lower part of the front pillar 217 and the side end part of a cowl inner panel 261 are joined to each other by a lower joint panel 262. In this lower joint structure, the pillar inner panel 231 has a pillar inner body 231a provided on the inside of the cab and an inner front-side flange 231b connectingly provided at the front edge of the pillar inner body 231a. This inner front-side flange 231b is provided so as to extend along the inner surface of the windshield glass and toward the center in the width direction of this glass.                Patent Document 1: International Patent Publication No. WO 2006/038430 A1 (claim 2, paragraph [0019], FIG. 2, FIG. 3).        
However, in the above-described conventional vehicular front structure described in Patent Document 1, as shown in FIG. 20, an upper notch 146b is formed in a side end flange 146a of the side inner panel 146, and a lower notch 161b is formed in the cowl inside flange 161a of the cowl inner panel 161. Therefore, stresses may concentrate in these notches 146b and 161b. 
Also, in the above-described conventional upper joint structure of front pillar, as shown in FIGS. 21 and 22, the upper joint panel 243 is provided on the cab inside of the pillar inner panel 231. Therefore, unless the above-described upper notch 146b (FIG. 20) is provided, the upper end of the inner front-side flange 231b of the pillar inner panel 231 interferes with the upper joint panel 243, so that the upper part of the inner front-side flange 231b cannot be extended to the front end part of the side inner panel 246. Therefore, if the front pillar 217 is made thin to improve the noticeability on the far side of the front pillar 217 as viewed from the driver sitting on a driver's seat, there arises a problem of decreased joint strength of the upper part of the front pillar 217.
Further, in the above-described conventional lower joint structure of front pillar, in addition to the need for the above-described lower notch 161b, there arises a problem of decreased joint strength of the lower part of the front pillar 217 if the front pillar 217 is made thin to improve the noticeability on the far side of the front pillar 217 as viewed from the driver sitting on the driver's seat.
An object of the present invention is to provide a vehicular front structure in which stresses do not concentrate in the upper joint part and the lower joint part of a front pillar, and even if the front pillar is made thin, the joint strength in the upper and lower parts of the front pillar can be improved.